A multifocal spectacle lens has a surface which effects the desired refractive power progression of the spectacle lens with this surface being characterized as a multifocal surface. This multifocal surface can be arranged at the object side or eye side and is supplemented by the second lens surface. The optical effect of this second lens surface, the refractive index of the lens material and the thickness thereof together with the multifocal surface determine the dioptric effect of the spectacle lens. The spectacle lens must be such that the ametropia of the user is optimally corrected.
Multifocal lenses are known for many years and are offered by several manufacturers. The multifocal lens of the applicant herein offered under the designation "GRADAL HS" is exemplary and is described in U.S. Pat. No. 4,606,622.
A further multifocal lens is known from U.S. Pat. No. 3,687,528. This lens has an umbilical meridian, that is, along a meridian, which partitions the multifocal surface into nasal and temporal regions, the surface astigmatism has the value 0. Because of this and other limiting features, the width of the near-vision portion, over which the surface astigmatism remains &lt;0.5 dpt, is small so that the user is forced to turn the head when looking toward the side even at small viewing angles.
Further multifocal lenses are described in the article of G. Guilino et al entitled "Neue progressive Flachen", journal DOZ, No. 11 of Nov. 20, 1980, pages 20 to 23. As shown in illustration 6 on page 23, the surface astigmatism laterally of the meridian and above all in the region of the progressive zone rapidly reaches such high values that these regions cannot be used for clear vision.
The multifocal lens known from U.S. Pat. No. 4,606,622 satisfies in each region all monocular and binocular requirements corresponding to the particular visual tasks as to sharp definition and compatibility.